/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cards.pay.paycardsrecognizer.sdk.camera.gles;

import androidx.annotation.RestrictTo;

import java.nio.FloatBuffer;

@RestrictTo(RestrictTo.Scope.LIBRARY)
public final class Drawable2d {
    private static final int SIZEOF_FLOAT = 4;

    /**
     * Simple square, specified as a triangle strip.  The square is centered on (0,0) and has
     * a size of 1x1.
     * <p>
     * Triangles are 0-1-2 and 2-1-3 (counter-clockwise winding).
     */
    private static final float RECTANGLE_COORDS[] = {
            -0.5f, -0.5f,   // 0 bottom left
            0.5f, -0.5f,   // 1 bottom right
            -0.5f,  0.5f,   // 2 top left
            0.5f,  0.5f,   // 3 top right
    };
    private static final float RECTANGLE_TEX_COORDS[] = {
            0.0f, 1.0f,     // 0 bottom left
            1.0f, 1.0f,     // 1 bottom right
            0.0f, 0.0f,     // 2 top left
            1.0f, 0.0f      // 3 top right
    };
    private static final FloatBuffer RECTANGLE_BUF =
            GlUtil.createFloatBuffer(RECTANGLE_COORDS);
    private static final FloatBuffer RECTANGLE_TEX_BUF =
            GlUtil.createFloatBuffer(RECTANGLE_TEX_COORDS);

    private FloatBuffer mVertexArray;
    private FloatBuffer mTexCoordArray;
    private int mVertexCount;
    private int mCoordsPerVertex;
    private int mVertexStride;
    private int mTexCoordStride;

    /**
     * Prepares a drawable from a "pre-fabricated" shape definition.
     * <p>
     * Does no EGL/GL operations, so this can be done at any time.
     */
    public Drawable2d() {
        mVertexArray = RECTANGLE_BUF;
        mTexCoordArray = RECTANGLE_TEX_BUF;
        mCoordsPerVertex = 2;
        mVertexStride = mCoordsPerVertex * SIZEOF_FLOAT;
        mVertexCount = RECTANGLE_COORDS.length / mCoordsPerVertex;
        mTexCoordStride = 2 * SIZEOF_FLOAT;
    }

    /**
     * Returns the array of vertices.
     * <p>
     * To avoid allocations, this returns internal state.  The caller must not modify it.
     */
    public FloatBuffer getVertexArray() {
        return mVertexArray;
    }

    /**
     * Returns the array of texture coordinates.
     * <p>
     * To avoid allocations, this returns internal state.  The caller must not modify it.
     */
    public FloatBuffer getTexCoordArray() {
        return mTexCoordArray;
    }

    /**
     * Returns the number of vertices stored in the vertex array.
     */
    public int getVertexCount() {
        return mVertexCount;
    }

    /**
     * Returns the width, in bytes, of the data for each vertex.
     */
    public int getVertexStride() {
        return mVertexStride;
    }

    /**
     * Returns the width, in bytes, of the data for each texture coordinate.
     */
    public int getTexCoordStride() {
        return mTexCoordStride;
    }

    /**
     * Returns the number of position coordinates per vertex.  This will be 2 or 3.
     */
    public int getCoordsPerVertex() {
        return mCoordsPerVertex;
    }

    @Override
    public String toString() {
        return "[Drawable2d: Rectangle]";
    }
}